That 10MW wind turbine on your 10,000m^2 of land will only get to that output by using wind blowing into it from other land.
So, if your neighbor builds another such turbine on his land, your output will drop.
So, you will have to pay your neighbors for not building such a turbine on their land. In that sense, you really need that area to get that output.
Having said that, ROI of wind turbines seems to be way better than that for photovoltaics, in almost every aspect. https://sites.google.com/site/anatomyofglobalclimatechangevj..., for example, gives you about 6 months to recover the energy investment of building a wind mill and 3 years for photovoltaics.
This is not an important effect. The optimal spacing for wind turbines is 5-15 times the rotor diameter, and the largest turbines are 75ft in diameter, giving a largest spacing of roughly ~ 1/4 mi. In the rare cases that this is an issue, property liens can handle the conflict.
Also, the effect is important. At 1/4 mile distance, you can only place about 20 or so on a square mile of land. Looking at http://en.wikipedia.org/wiki/Wind_turbine#Horizontal_axis_wi..., that gives you less than 18MW peak power.
That same square mile has 2M plus m^2. So, you would need only 10W per m^2 peak solar power to beat that wind turbine.
Yes, there is lots of hand waiving here. For example, I am assuming equal duty cycle; that will vary with location. The crux still is that there is way less wind power than solar per m^2.
This is a misleading number for my point that wind is denser than solar. For solar, the 22W/m^2 is spread out evenly an area, and you must put something (either photovoltaic or a mirror) to collect it. For wind, you only need a single turbine to effectively cover a relatively large area. The density number comes from the fact that, by virtue of how winds are generated and blow, you can't just stick a second turbine right next to the first one. From a cost per kWh perspective, the important number is more like the number of watts generated by single turbine with a 1 meter x 1 meter footprint.